The role of 2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone (BHT quinone methide) in the metabolism of butylated hydroxytoluene.

Male rats were fed 5.45 mmol/100 g diet butylated hydroxytoluene (BHT) or 2,6-di-tert-butyl-4-hydroxymethylphenol (BHT alcohol) in either a standard or purified diet for 1 wk, after which their livers were analysed for levels of unconjugated BHT metabolites and their blood clotting times were assayed. The BHT quinone methide, 2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone, was only found in appreciable concentrations (6-9 micrograms/g liver) in the livers of rats given BHT. For rats fed the purified diet, BHT and BHT alcohol caused significant reductions of the prothrombin index to 23 and 70%, respectively, of the control value, though rats fed the standard diet were not similarly affected. Liver concentrations of BHT in rats fed BHT alcohol also varied according to diet, indicating that the metabolic pathway may be affected by diet. Biliary excretion of the quinone methide was observed in rats given 140 mg BHT alcohol ip.